1. Field
The present disclosure generally relates to the application of film over a substrate, and deals more particularly with a method and apparatus for applying and trimming a film material along a surface of an elongate structural member, such as a composite stringer.
2. Background
Composite and other structures may be bonded together using a structural film adhesive material which may include a carrier such as a scrim for controlling bondline thickness. For example, in the aircraft industry, a composite stringer may be joined to another composite part such as a skin by co-bonding, or in a secondary bonding operation using a structural film adhesive material that is applied over the surface of a flange on the stringer. The stringer flange with the applied film adhesive is placed against the skin and the film adhesive is cured using thermal or other techniques.
Preparing long composite structural members such as aircraft stringers for an adhesive bonding operation is a multi-stage process that is currently time consuming and labor intensive. A film adhesive material is manually rolled out to the length of the stringer, which may be 90 feet or more in the case of aircraft applications, and a protective poly backer must then be removed from the film. The entire length of the film material is then flipped over by a team of workers in order to place the backside of the film adhesive on a base flange of the stringer. Workers then manually trim excess film material away from the edges of the base flange. This hand trimming technique may be tedious, time-consuming and presents the risk of damage to edges of the base flange, particularly where the flange is beveled. During hand trimming, foreign object debris may be produced which, if adhered to the stringer, may affect the desirability of the bond. After trimming, the film material is smoothed by hand following which the stringer is flipped over and vacuum bag processed in order to compact the film material against the stringer base flange.
Accordingly, there is a need for a method and apparatus for applying film material to long structural members that reduce dependence on manual labor, and which improve process flow time. There is also a need for a method and apparatus for applying film material that provide rapid trimming of excess material to match structural details, and which eliminate the need for vacuum bag compaction.